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Recommend some 'standard' carbide inserts

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  • Recommend some 'standard' carbide inserts

    I'm making some new toolpost blocks for my Phase-II QC lathe toolpost, and I want to make some that take carbide inserts directly.

    Aloris makes some, it's basically the standard dovetail block with a nose machined to take one form or another of replaceable carbide insert. So instead of buying a $25 toolpost block and clamping a $45 carbide lathe toolholder in it, I'm making a one-piece block.

    However, I know little or nothing about replaceable bits or carbide. I have a few that I bought used or traded for, but I don't know the designations of the inserts, how to properly measure them, or how to order more.

    I'm making these blocks from scratch, so I can have them take any insert I want, within reason. So the question is, what would be a good selection of "standard" shapes and sizes to go with? I want a common size that I can get from a variety of suppliers, and will probably still be around years from now.

    I'd like to order a box each (10 pieces) of, say, three different sizes or shapes, plus the holddown bolts, screws or clamps, and then machine the toolposts to hold them.

    I'm thinking a triangular insert first, in a standard size I can get in a common variety, including chipbreaker or flat, and perhaps in varying nose radii.

    Then a trapezoidal insert, or maybe a long diamond, and possibly a round, to do an inside radius on parts.

    Could someone recommend a good, standard, size and style for me? It's an 11" lathe and I'm using an AXA-size toolpost. The blocks can take up to a 1/2" tool. The largest carbide tool I have is a 1/2" dia. boring bar that takes a triangular insert about 9/16" on a side, held down by a center screw. That's a good size, but how do I tell what kind or style insert it is?

    Doc's Machine. (Probably not what you expect.)

  • #2
    Take a look at TNMG inserts. They are widely available, cost about $2 each, both sides are usable. You get 6 good cutting edges out of each insert.


    • #3
      you may think about surfing ebay for the "mother load" of inserts and just building holders for whatever you find.

      more fun than seeing 50 inserts sell for 1 penny and passing it up because they are not for your style holder.


      • #4
        Here is a handy page to explain what all those letters and m=numbers mean.-

        I use the CNMG style,85*diamond,good for general purpose roughing in alloy and stainless steel.

        The common TPG 322 is also good to have around,general purpose for non-ferrous metals and cast iron.

        Oh,also they are a good place to get inserts-

        You might want cheap or you might want good,if you want the best get Kennametal,if you want cheap any of the others will do

        [This message has been edited by wierdscience (edited 11-16-2004).]
        I just need one more tool,just one!


        • #5
          Unless you have a heavy lathe with plenty of power you may want to look at the positive rake tools like ccmt tcmt etc. The inserts suggested above will require more machine and tricky machining to make the holder. The positive rake tools will have a side clearence angle made into them and you can machine a flat pocket with a tapered emill then drill and tap hole in center for holding in place. The negative rake tools like CNMG require the tool holder to be made so that insert is held in manner to produce clearance plus they use a cam lock screw and a clamp to secure insert. They work very well and are most common to industry but require more power as chip is forced up rake face and back on itself. Positive rake tools allow the chip to slide down rake face and away from work using less power.



          • #6
            Kennametal k 680 ,I used to gang turn flame cuts and plasma cut stainless circles, last twice as long as the cheapo insert.

            now thats a fine insert(cost more too).


            • #7
              Got a good start!

              The teach at the college gave me a small flyer that's helping decode the insert labelling, and I've been comparing that with an Airgas catalog that has some good info and clear photos.

              I hadn't thought about having to machine rake into the toolholder itself... I would definitely want an insert that I can simply machine a flat/level pocket for...

              I bandsawed the first bar into blocks while I was at the college- a heavy cutoff saw makes for easy work. I'll have to get one one of these days.

              That got me six "standard" block sizes (the usual all-purpose square-tool/boring bar holder) and four "extended" a bit to give me room to machine for the inserts. Once I have 'em roughed (still have to by a bug 60-degree dovetail cutter) I'll have to order some inserts and finish-mill to fit.

              Doc's Machine. (Probably not what you expect.)


              • #8
                Doc, You may find this interesting:


                I use TCMT, DCMT and CCMT inserts quite a bit and also some Aloris #16, TPG holders.

                These are all positive rake tools. The site has lots of other info including magic decoder sheets for insert designations.

                One pretty important thing is to look at the range of feed and depth of cut for which the inserts are designed. They are made for specific feeds (finishing, medium, roughing, etc.) and get pretty complicated to outfit the shop with.

                If you look on that site under Kennametal inserts, click on the link for <inserts><kennametal><dcmt> and you will see just a small part of the chipbreaker info.

                The negative rake tools mentioned are intended primarily for heavy feed rates. In some cases, you would need upwards of a 0.020" finishing pass to size to keep these "N" inserts humming.



                • #9
                  Another link from a very enjoyable site:


                  • #10
                    OK Doc,

                    Let me get you into it!! Take a look at these:



                    on Metal Web News under: METAL REMOVAL [Machining, turning, boring drilling, etc.]

                    PS If the second article is unintelligible, its cuz I penned it. : )


                    • #11
                      I prefer inserts like CCMT (80 degree diamond) and such that will both turn and face in the same setting.

                      Inserts like the triangle variety will not do that.


                      • #12
                        Check this out. Carbide tool holders for small machines.